Police say the bomber drove his explosives-laden truck into the concrete blast walls outside police headquarters in the town of al-Salam, about 75 kilometers northeast of Baghdad and close to the city of Baquba.

Baquba and its surroundings saw an increasing number of attacks as part of a nationwide increase in the violence that has gripped Iraq this year.

The level of violence in the country rose sharply after security forces stormed a Sunni protest camp in northern Iraq in April. Reports say more than 5,500 people have been killed since April.